JPS6247425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the exhaust amount of a paint baking/drying oven, which controls the exhaust amount by controlling the rotation of an exhaust fan.

The amount of heat inside the drying oven, which is used to bake and dry a metal plate after applying a base coat, is extremely large, and the amount of solvent vapor during painting is also large, causing an explosion if the amount of solvent vapor fills the oven. In order to prevent this from occurring, the atmosphere inside the furnace was drawn out of the furnace using an exhaust fan, and the rotational speed of the exhaust fan was kept constant to ensure a constant exhaust volume.

However, during the heat load of the drying oven, the rate of removal by exhaust air is extremely large, ranging from 70% to 80% of the total heat load.
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In order to alleviate the loss of heat due to such exhaust, conventional methods have been to exhaust the air inside the drying oven by opening and closing a damper that is adjusted and operated by an electromagnetic switch with a timer, and to rotate and stop the exhaust fan using an electromagnetic switch with a timer. There are methods, but all of these methods open and close the damper and rotate and stop the exhaust fan regardless of the type and amount of paint, so they not only reduce the operating rate but also make it difficult to adjust the exhaust volume. This took too much time, resulting in a delay in control response, and the desired effect could not be achieved.

In view of the above-mentioned circumstances, the present invention is designed to control the exhaust volume by freely setting the rotation speed of the exhaust fan according to the baking drying conditions corresponding to the material to be dried. A frequency converter is connected to a power source, the indicated value of the frequency converter is determined based on the distance between the axes of the coating machine rolls, and the frequency converter is operated while the temperature is rising in the furnace and while waiting before introducing the dried material to be baked. The motor for driving the exhaust fan is rotated at low speed, and then the temperature inside the furnace is increased through the frequency converter by detecting the temperature rise inside the furnace using the temperature sensor.
A method for controlling the exhaust amount of a paint baking drying oven, characterized in that the rotation of the exhaust fan driving motor is made larger than during standby before introduction of the drying material to be baked.

Embodiments of the present invention will be described with reference to drawings showing an example of an apparatus to which the present invention is applied.

A conveyor 3 with a large number of wickets 2, 2, etc. attached to its running section is installed in a drying oven 1 for baking and drying coated metal sheets. The painted metal plates A to be applied are sequentially supported and transported by the wicket 2,
The coated metal plate is baked and dried by a gas burner (not shown) between the inlet 4 side and the outlet 6 side.

Next, the end of the conduit 8 that communicates with the hot air discharge part 7 formed on the upper wall of the drying oven 1 is connected to the inlet side of the exhaust fan 9, and the exhaust pipe 10 connected to the outlet side of the exhaust fan 9 is subjected to exhaust treatment such as deodorization. A device 11 is interposed.

The exhaust fan 9 is driven by an exhaust fan drive motor 12.
A frequency converter 14 is attached to the power supply 13 (see FIG. 2).

The frequency converter 14 forms an indicator part 15 that indicates an indicator value that allows the power frequency to be converted to a desired frequency between 25 Hz and 50 Hz. The rotation speed of the exhaust fan 16 of the exhaust fan 9 is set to 730 r.pm when power is supplied to the drive motor 12, and 1460 r.pm when 50 Hz power is supplied. The rotation speed of exhaust fan 16 is from 730r.pm to 1460r.pm
It is configurable between.

The coating machine 5 has a coating roll 17 and a applying roll 1.
A metal plate is passed between the coating roll 17 and the applying roll 18 to form a coated metal plate.
A measuring device 19 is provided to measure the distance between the axes, and the amount of coating film can be recognized based on the distance between the axes.

In other words, when applying through a metal plate of a predetermined thickness, the thickness of the coating film is proportional to the distance between the axes, or in other words, the gap between the rolls, and the thickness of the coating film is large using the same coating material. means that the amount of paint is large, and the amount of paint that is large means that the amount of solvent is large, and the amount of solvent evaporation is proportional to the distance between the axes for the same paint. The distance between the axial center of the applicator roll 17 and the axial center of the application roll 18 of the atomizer 5 is measured, and the set value of the frequency converter 14 is determined in accordance with this measured value.

Further, the set value of the frequency converter 14 is determined by taking into consideration the type of paint, the type of solvent in the paint, and the like.

A temperature sensor 20 is provided in the exhaust treatment device 11, and the temperature sensor 20 and the exhaust fan drive motor 12 are connected via a controller 21. The exhaust fan 16 is formed to rotate at a large speed.

Each member is arranged in this way and operated as follows.

That is, the instruction value of the frequency converter 14 is determined based on the distance between the axes of the paint rolls, the frequency of the power to be supplied is selected, and the rotation speed of the exhaust fan 16 is determined.

Next, the drying furnace 1 is started, and while the atmosphere inside the drying furnace 1 is being heated up to the operating temperature, that is, while the temperature inside the furnace is being raised, the rotation of the exhaust fan 16 is set to a low speed, and the temperature inside the furnace is gradually increased. When the predetermined working temperature is reached, the temperature sensor 20 detects a temperature rise in the furnace, and the frequency converter 14 increases the rotational speed of the exhaust fan drive motor 12.

The rotational speed of the exhaust fan drive motor 12 during the temperature rise inside the furnace is approximately 1/3 to 1/6 of that during drying work, and the painted metal plates 1, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 5, 6, 5, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, When the process of baking and drying the paint begins and evaporation of the solvent in the paint begins to occur, the rotation of the exhaust fan 16 is increased via the temperature sensor 20, and the hot air passes through the hot air exhaust section 7.
The exhaust gas is discharged into the atmosphere via a conduit 8 and an exhaust pipe 10.

The present invention determines the indicated value of the frequency converter based on the distance between the axes of the atomizer rolls, in other words, the gap between the rolls. The exhaust fan drive motor is rotated at a low speed, and then the temperature sensor detects a rise in the temperature in the furnace, and the frequency converter detects the rotation of the exhaust fan drive motor while the temperature inside the furnace is rising. The exhaust amount is adjusted by controlling the speed of the exhaust fan drive motor to increase the rotation of the exhaust fan.
Through a frequency converter, the rotational speed of the exhaust fan can be set to the optimum condition according to the condition of the material to be dried, i.e. the amount of paint, the type of paint, the starting condition of the drying furnace, and the working condition, so the atmosphere inside the furnace can be adjusted. The amount of exhaust gas can be controlled according to the amount of solvent vapor inside, reducing the rate of exhaust gas removal during the total heat load and mitigating heat loss.
Energy saving effects can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view showing an example of a device to which the present invention is applied, Fig. 2 is an explanatory diagram showing the main parts of an exhaust fan drive system, and Fig. 3 is an example of determining the indicated value of a frequency converter. FIG. 1... Drying oven, 2... Wicket, 3... Conveyor,
5... Painter, 9... Exhaust fan, 12... Exhaust fan drive motor, 13... Power supply, 14... Frequency converter, 1
6...Exhaust fan, 20...Temperature sensor.

Claims (1)

[Claims] 1. Connect a frequency converter to the power supply of the exhaust fan drive motor, determine the indicated value of the frequency converter based on the distance between the axes of the coating machine roll, and wait while the temperature inside the furnace is rising and before introducing the dry matter to be baked. Inside the furnace, the exhaust fan driving motor is rotated at a low speed via the frequency converter, and then, when the temperature rise in the furnace is detected by the temperature sensor, the temperature is increased via the frequency converter during the temperature rise in the furnace, and the motor is rotated at a lower speed than during the standby period before introducing the dried material to be baked. A method for controlling the displacement of a paint baking drying oven, characterized in that the rotation of the exhaust fan driving motor is increased.